Direct thermal printable film and laminate

ABSTRACT

A new direct thermal printable media includes an optically transmissive film that gives both form and protection to a layer of thermosensitive imaging material on a back surface of the film. Concentrations of heat applied to a front surface of the film form images within the thermosensitive layer that are visible through the film. A substrate is laminated to the thermosensitive layer on the back surface of the film for providing additional support independently of physical and chemical properties required for directly supporting thermosensitive imaging material.

[0001] This application claims the benefit of U.S. ProvisionalApplication No. 60/026,501, filed on Sep. 23, 1996, which provisionalapplication is incorporated by reference herein.

TECHNICAL FIELD

[0002] The invention relates to the field of direct thermal printing andespecially to media used for such printing.

BACKGROUND

[0003] Direct thermal printable media is most widely used as facsimilepaper but is also used in printers and in other applications requiringpermanent imaging such as tags, tickets, and labels. In contrast toprinting technologies that involve the transfer of ink from one locationto another, direct thermal printing uses a special printable media thatincorporates a color developing mechanism. Images are formed by exposingthe color developing mechanism to concentrations of heat that producelocalized chemical reactions involving a change of color (usually lightto dark). The color developing mechanism is provided by athermosensitive imaging material containing heat reactive chemicals suchas leuco dyes or metallic salts.

[0004] Since direct thermal printing only involves the transfer of heat,printing of direct thermal media is simple and clean. Other advantagesinclude low cost, low noise, and high speed. However, thethermosensitive imaging material is susceptible to damage from exposureto various environmental conditions including abrasion, heat, light, andchemicals such as oils, fats, blood, alcohol, solvent, and water. Muchof this damage can be limited by applying protective coatings that blockunwanted environmental interactions with the thermosensitive imagingmaterial.

[0005] For example, U.S. Pat. No. 4,711,874 to Yuyama et al. suggestsuse of a water-soluble polymeric material as a protective overcoatingfor providing physical and chemical resistance. U.S. Pat. No. 4,717,709to Suzuki suggests use of a polyolefin resin for similar purposes. U.S.Pat. No. 4,886,774 to Doi discloses a protective overcoating containingUV blockers. U.S. Pat. No. 5,286,703 to Wachi et al. discloses use ofmultiple protective overcoat layers including a first layer ofwater-soluble or water-insoluble polymers for chemical resistance and asecond layer containing UV blockers.

[0006] The thermosensitive imaging material is applied as a coating to asubstrate surface. Printing takes place by exposing the coating to apattern of heat conducted from a thermal print head located adjacent tothe substrate surface containing the coating of thermosensitive imagingmaterial. The coating takes the form of the substrate surface includingany irregularities or roughness in the surface. Accordingly, any surfaceirregularities in the thermosensitive coating vary spacing between thethermal print head and different points on the coating, causing unwanteddissipations of heat that interfere with image quality.

[0007] Two solutions are known to limit irregularities in thethermosensitive coating. One is to use only substrates with smoothsurfaces. The other is to apply an undercoating between the substrateand the thermosensitive coating. The undercoating covers irregularitiesin the substrate surface and provides a smooth base for applying thethermosensitive coating. An example is found in U.S. Pat. No. 4,711,874to Yuyama et al.

[0008] Protective overcoatings shield thermosensitive coatings fromenvironmental interactions, and undercoatings provide a smooth base forapplying thermosensitive coatings; but both add cost and complexity todirect thermal printable media. Also, the undercoatings can change theappearance or other desired properties of the substrates. However,without an undercoating, the choice of substrate is even more limited.

SUMMARY OF INVENTION

[0009] My invention obviates the need for both overcoatings andundercoatings that separately protect and support coatings ofthermosensitive imaging material in direct thermal printable media.Coatings of thermosensitive imaging material can be used with a widervariety of underlying substrates without resort to undercoatings,because surface features of the thermosensitive coating are no longerlinked to the surface features of the underlying substrates.

[0010] An example of my invention as a direct thermal printable laminateincludes two adjacent substrates, one of which is preferably anoptically and thermally transmissive film. A thermosensitive imaginglayer is located adjacent to a back surface of the transmissive film,and the back surface of the transmissive film is bonded to a frontsurface of the other substrate for laminating the transmissive film tothe other, substrate. The thermosensitive imaging layer is reactive totransmissions of heat through the film (which is thermally transmissive)for forming images within the thermosensitive imaging layer that arevisible through the same film (which is also optically transmissive).

[0011] Preferably, the thermosensitive imaging layer is bonded directlyto the back surface of the film and indirectly to the front surface ofthe other substrate through the intermediacy of an adhesive layer.Accordingly, the thermosensitive imaging layer takes the form of theback surface of the film rather than the form of the front surface ofthe other substrate.

[0012] In addition to functioning as a transmitter of both light andheat, the film can perform two other main functions—first, as aprotective covering for the thermosensitive imaging layer and second, asa base for giving desired form to the thermosensitive imaging material.Thus, my invention permits many more materials to be used as substratesfor direct thermal printing while protecting the thermosensitive imaginglayer from unwanted environmental interactions.

[0013] My new laminate is printable by applying concentrations of heatfrom a thermal print head to the front surface of the film resulting inthe formation of images within the thermosensitive imaging layer. Thefilm is preferably much thinner in thickness than the other substrate tomore efficiently transmit heat from the thermal print head to thethermosensitive imaging layer. Thicknesses less than 10 microns arepreferred.

[0014] Another example of my invention as self-wound direct thermalprintable tape includes a similarly transmissive film. A release layeris applied to a front surface of the film, and a thermosensitive imaginglayer is applied to a back surface of the film. The thermosensitiveimaging layer is reactive to transmissions of heat through the film forforming images within the thermosensitive imaging layer. Adhesive layersare applied to front and back surfaces of a substrate. A first of theadhesive layers bonds the substrate to the film, and a second of theadhesive layers is intended for bonding the film and substrate toanother substrate or object.

[0015] However, prior to bonding the film and substrate to anothersubstrate or object, the film and substrate are unwindable from a rollin which the second adhesive layer is in contact with the release layer.

[0016] Again, a wider selection of substrates can be used with my newdirect thermal printable tape, because the transmissive film providesthe thermosensitive imaging layer with a desired form as well as aprotective covering against exposure to environmental hazards. Therelease layer on the front surface of the film eliminates any need for aseparate release liner to protect the second adhesive layer prior touse. Also, since the thermosensitive imaging material is first coated onthe film rather than on the underlying substrate, smaller productionruns are more economical because the coated film can be divided for runswith different substrates.

[0017] In fact, a thin thermally transmissive film coated with athermosensitive imaging material in accordance with my invention can bemade as either an intermediate product intended for lamination toanother substrate or as a final product that can be imaged prior to orin conjunction with its use. Preferably, the film is both thermally andoptically transmissive and has a thickness no greater than 10 microns.

DRAWINGS

[0018]FIG. 1 is a schematic cross section of a first embodiment of myinvention as a new direct thermal printable laminate.

[0019]FIG. 2 is a schematic cross section of a second embodiment of myinvention as a similar laminate having additional layers.

[0020]FIG. 3 is a schematic cross section of a third embodiment of myinvention as a new direct thermal printable tape.

[0021]FIG. 4 is a schematic cross section of the third embodiment woundinto a roll.

[0022]FIG. 5 is a diagram of a production line for coatingthermosensitive imaging material on a thin film.

[0023]FIG. 6 is a diagram of a production line for coating a substrateand for laminating the coated film to the coated substrate.

[0024]FIG. 7 is a diagram of a printing sequence for direct thermalprinting of the new laminate.

DETAILED DESCRIPTION

[0025] Illustrated by FIG. 1 is a direct thermal printable laminate 10having two adjacent substrates 12 and 14 joined by a layer 16 ofthermosensitive imaging material and by a layer 18 of adhesive. Thelayer 16 of thermosensitive imaging material is bonded to the substrate12, and the two substrates 12 and 14 are bonded to each other by theadhesive layer 18. Concentrations of heat from a thermal print head (notshown until FIG. 7) can be applied to the first substrate 12 for formingimages in the layer 16 of thermosensitive imaging material.

[0026] The substrate 12, which is preferably an optically and thermallytransmissive film, has thickness “T₁” measured between front and backsurfaces 20 and 22. The thickness “T₁” is preferably limited to 10microns or less (e.g., 6 microns) to avoid interfering withtransmissions of heat through the film 12 required for forming imageswithin the thermosensitive imaging layer 16. The images so formed arevisible through the film 12. Preferably, the film 12 is made from astrip of flexible material such as polyester, which is capable of makingthe required transmissions of light and heat as well as capable ofretaining its form at the required thickness “T₁”. Other possible filmmaterials include polyethylene, polypropylene, acetate, or otherpolyolefins.

[0027] Various coatings (not shown) can be applied to the film 12 toprovide additional Protection for the thermosensitive imaging layer 16form exposure to potentially damaging environmental conditions. Forexample, the film 12 can be coated with UV blockers as described in U.S.Pat. No. 4,886,774 to Doi, which is hereby incorporated by reference.

[0028] The thermosensitive imaging layer 16 preferably contains a dyeprecursor such as a pale or colorless leuco dye and a color former suchas an acidic developer that causes the leuco dye to undergo a colortransformation in the presence of heat. The dye precursor and colorformer are separately microencapsulated or otherwise separated toprevent their interaction prior to the application of a predeterminedamount of heat. Other color developing mechanisms could also be usedincluding metallic salt color former chemical systems.

[0029] The substrate 14 can be selected from a wider variety ofmaterials including those that do not have physical and chemicalproperties required for directly supporting thermosensitive imagingmaterial. Examples include high-ground wood content paper, high-strengthfilms such as polyvinyl plastics, and woven or non-woven fabrics, aswell as other coarse materials that would otherwise not be suitable fordirect thermal printing. Front and back surfaces 24 and 26 of thesubstrate 14 are separated by a thickness “T₂” that can be much greaterthan the thickness “T₁”. For example, the thickness “T₂” can exceed thethickness “T₁” by an order of magnitude or more.

[0030] Preferably, the layer 16 of thermosensitive imaging material isapplied as a coating that takes the form of the back surface 22 of thefilm 12. Accordingly, the back surface 22 of the film must be smooth formounting the layer 16 of thermosensitive imaging material at a constantdistance from a print head. However, the front surface 24 of thesubstrate 14 can be much rougher. For example, the front surface 24 ofthe substrate can have an average peak-to-valley roughness that islarger than an average peak-to-valley roughness of the back surface 22of the film. In fact, the peak-to-valley roughness of the front surface24 can exceed an average thickness of the thermosensitive imaging layer16 while the similarly measured roughness of the back surface 22 ispreferably much less.

[0031] The adhesive layer 18 can be applied as a coating on the frontsurface 24 of the substrate 14. Preferably, the adhesive layer 18 isformed by a pressure-sensitive adhesive to form a permanent bond withthe film 12. If mutually compatible, the adhesive layer 18 can be bondeddirectly in contact with the thermosensitive imaging layer 16. Possibleexamples include acrylics, water-borne adhesives, hot melts, andrubber-based extrusions.

[0032] A direct thermal laminate 30 shown in FIG. 2 includes additionallayers for performing specialized functions. Similar to the precedinglaminate 10, the laminate 30 includes an optically and thermallytransmissive film 32 and a substrate 34. The film 32 has front and backsurfaces 40 and 42, and the substrate 34 has front and back surfaces 44and 46. Layer 36 of thermosensitive imaging material is located adjacentto the back surface 42 of the film 32. Layer 38 of adhesive is locatedadjacent to the front surface 44 of the substrate 34.

[0033] However, between the thermosensitive layer 36 and the adhesivelayer 38 is a barrier layer 48 that prevents migration of contaminantsfrom the adhesive layer 38 to the thermosensitive layer 36. This permitsa wider range of materials to be used in the adhesive layer 38. Suitablebarrier materials include water-borne or UV curable varnishes orprimers.

[0034] The thermosensitive layer 36 is preferably bonded directly to theback surface 42 of the film 32 and is bonded indirectly to the frontsurface 44 of the substrate 34 through the intermediacy of the adhesivelayer 38. Any layers located between the thermosensitive layer 36 andthe adhesive layer 38, such as the barrier layer 48, are preferablybonded in succession to the thermosensitive layer 36 so that theadhesive layer 38 provides the final connection between the film 32 andthe substrate 34.

[0035] A friction-reducing coating 50, such as silicone orpoly(tetrafluororthene), can be applied to the front surface 40 of thefilm 32 to protect thermal print heads from excessive wear. This permitsa wider range of materials to be used as the film 32. A suitable coatingthat also functions to clean the thermal print heads is disclosed in myrecently issued U.S. Pat. No. 5,658,661 entitled “Matted Release Coatfor Self-wound Thermal Printable Facestock”, which is herebyincorporated by reference. The front surface 40 can also be matted orotherwise made receptive to conventional printing inks. In addition,printing inks 52 and 54 can be applied to the front and back surfaces 44and 46 of the substrate 34. The printing ink 52 is visible through thefilm 32.

[0036] My invention arranged as a direct thermal printable tape 60 isillustrated by FIGS. 3 and 4. The tape 60 has a laminate constructionsimilar to the preceding embodiments 10 and 30 but is also arranged forbeing affixed to another substrate or object (not shown).

[0037] A film 62 and a substrate 64 give form to the tape 60 and tovarious layers applied to them. A release layer 80 is applied to a frontsurface 70 of the film 62, and a thermosensitive imaging layer 66 isapplied to a back surface 72 of the film 62. Adhesive layers 68 and 78are applied to front and back surfaces 74 and 76 of the substrate 64.The adhesive layer 68 is in contact with the thermosensitive layer 66for bonding the film 62 and the substrate 64 together.

[0038] The adhesive layer 78 provides for attaching the tape 60 toanother substrate or object. The composition and pattern of the adhesivelayer 78 are adjusted to meet the requirements of its use. Ordinarily,the adhesive layer 78 is expected to be pressure sensitive, but theadhesive layer 78 could also exhibit other qualities such asco-adhesion, repositionability, removability, and resistance to cold.

[0039] A release layer 80 protects the adhesive layer 78 prior to use.The composition of the release layer 80 is tied to the composition ofthe adhesive layer 78 so that the release layer 80 exhibits low adhesionto the adhesive layer 78. Liquid-curable silicone generally works wellas a release coat. The release layer is preferably applied with a mattedfinish to prevent the accumulation of debris on the print head. Anexample of such a finish is disclosed in my above-identified U.S. Pat.No. 5,658,661.

[0040] When wound together into a roll 82 as shown in FIG. 4, theadhesive layer 78 on the back surface 76 of the substrate 64 contactsthe release layer 80 on the front surface 70 of the film 62. The film 62and substrate 64 can be unwound together from the roll 82 by separatingthe layers of adhesive and release 78 and 80.

[0041] The film 62 is ordinarily transparent (or at least translucent)to provide an optical path for viewing the images produced in thethermosensitive layer 66, and the substrate 64 is ordinarily opaque toprovide a background for the images. However, the substrate 64, like thefilm 62, could be made optically transmissive for substituting otherbackgrounds. For example, the other substrates or objects to which thetape 60 is attached could be visible through both the film 62 and thesubstrate 64.

[0042] Alternatively, any one of the films 12, 32, or 62 in thepreceding embodiments could be made opaque in combination with makingtheir corresponding substrates 14, 34, or 64 transparent, therebyrequiring images in the corresponding thermosensitive layers 16, 36, and66 to be viewed in reverse through the substrates 14, 34, or 64. Thefilms 12, 32, or 62 could also be made opaque to visible light but usedin combination with a thermosensitive material that is infrared readablethrough the films. Thus, the thermosensitive imaging material—can beviewed (or read) through either the films 12, 32, or 62 or theircorresponding substrates 14, 34, or 64 but is preferably imaged bytransmissions of heat through the films 12, 32, or 64 alone.

[0043] My new laminates 10, 30, and 60 can be made by a single inlineprocess or by a series of separate processes involving various steps ofcoating, printing, and laminating. For example, FIG. 5 illustrates anin-line process for separately preparing a film 92 similar to the films12, 32, and 62 of the preceding embodiments. The film 92 is unwound froma roll 116 and is fed through a series of coaters 118, 120, and 122. Thecoater 118 applies a layer of friction-reducing material 110 to a frontsurface 100 of the film 92. The coater 120 applies a layer ofthermosensitive imaging material 96 to a back surface 102 of the film92. After curing, the coater 122 applies a layer of barrier material 108over the layer of thermosensitive imaging material 96. The coated film92 is then fed through a longitudinal slicer 124 that divides the coatedfilm 92 into narrower strips 92 a, 92 b, and 92 c, which are wound ontorolls 126 a, 126 b, and 126 c. Each of the rolls 126 a, 126 b, and 126 cis an intermediate product that can be combined with a number ofdifferent substrates.

[0044] In FIG. 6, the separate roll 126 a is unwound together with aroll 128 of a substrate 94 similar to the substrates 14, 34, and 64. Thesubstrate 94 is fed through a printer 130 for applying ink 112 and 114to front and back surfaces 104 and 106 of the substrate 94 and through acoater 132 for applying an layer of adhesive 98 to the front surface104. The printer 1.30 can be a thermal or a non-thermal printer. Alaminator 134 joins the back surface 102 of film 92 a containing thesuccessive layers of thermosensitive imaging material 96 and barriermaterial 108 to the front surface 104 of the substrate 94 containing thelayer of adhesive 98 creating a new direct thermal printable laminate140. The new laminate 140 is wound into a roll 142 ready for directthermal printing.

[0045] The coating stations can be used in different combinations, andadditional coating stations can be used to apply other layers to thefilm 92 or substrate 94. For example, the layer of friction-reducingmaterial 110 on the front surface 100 of the film 92 could be fashionedas a release, and another layer of adhesive could be applied to the backsurface 106 of the substrate 94 for making a self-wound tape. With thefriction-reducing material 110 functioning as a release, the layer ofadhesive material 98 could alternatively be applied over the layer ofbarrier material 108 on the back surface 102 of the film 92 beforewinding the film 92 onto separate rolls 126 a, 126 b, and 126 c.Separate steps could also be used to prepare the substrate 94 beforeunwinding from the roll 128 (such as adding perforations), or more stepscould be performed on the film 92 a and the substrate 94 in parallel.

[0046] A method of printing the new laminate 140 is shown in FIG. 7. Thelaminate 140 joining the film 92 a and the substrate 94 is unwound fromthe roll 142 and is fed into a thermal printer 144 having a thermalprint head 146. The thermal print head 146 applies heat to the frontsurface 100 of the film 92 a for producing images within the layer ofthermosensitive imaging material 96. The layer of friction-reducingmaterial (or release) 110 on the front surface 100 of the film 92 aprotects the thermal print head 146 from excessive wear. A lateralslicer 148 divides the laminate 140 into individual sheets 150 accordingto their purpose (e.g., tag, ticket, or label). Alternatively, thelaminate 140 could be perforated or aligned with a tear bar for manuallyseparating the laminate into the individual sheets 150. The laminate 140could also be sliced into sheets 150 prior to printing.

[0047] In addition, lamination could take place in the printer 144. Forexample, the film 92 a and substrate 94 could be separately fed into theprinter 144; and either prior to or after imaging the thermosensitiveimaging material 96, the film 92 a and the substrate 94 could belaminated together. This would enable direct thermal printing of avariety of different substrates at the printer 144, using the film 92 aas both a print medium and a portion of the laminate.

[0048] While the invention has been described with respect to itspreferred embodiments, many other applications of the invention will beapparent to those of skill in the art. For example, I have described thespecial advantages of my invention for use with self-wound thermallyprintable labels. However, conventional layer label structures withrelease liners can also be constructed in accordance with my invention,as well as a broad variety of other direct thermal print media includingsubstrates that are normally not susceptible to direct thermal printing.

[0049] Although I prefer to bond a thin film containing thethermosensitive imaging layer to a more substantial substrate using alayer of adhesive, other well-known types of bonding can also be used,including heat or static seals. The various layers, including the layerof thermosensitive imaging material, while preferably continuous, canalso be laid down in patterns to suit particular applications.

I claim:
 1. A direct thermal printable laminate comprising: a thermallytransmissive film having front and back surfaces; a thermosensitiveimaging layer on said back surface of the thermally transmissive film;said thermosensitive imaging layer having a color developing mechanismreactive to transmissions of heat through said thermally transmissivefilm for forming images within said thermosensitive imaging layer; asubstrate for supporting said thermally transmissive film also havingfront and back surfaces; and a bond between said back surface of thethermally transmissive film and the front surface of the substrate forlaminating said thermally transmissive film to said substrate.
 2. Thelaminate of claim 1 in which said bond is formed by an adhesive layerlocated between said thermosensitive imaging layer and the front surfaceof the substrate.
 3. The laminate of claim 2 in which saidthermosensitive imaging layer is bonded directly to said back surface ofthe transmissive film and indirectly to said front surface of saidsubstrate through the intermediacy of said adhesive layer.
 4. Thelaminate of claim 2 in which any layers located between saidthermosensitive imaging layer and said adhesive layer are successivelybonded to said thermosensitive imaging layer.
 5. The laminate of claim 4further comprising a barrier layer located between said thermosensitiveimaging layer and said adhesive layer for preventing migration ofcontaminants from said adhesive layer to said thermosensitive imaginglayer.
 6. The laminate of claim 2 in which said back surface of thetransmissive film and said front surface of the substrate haverespective surface forms, and said thermosensitive imaging layer takesthe form of said back surface of the transmissive film.
 7. The laminateof claim 6 in which said thermosensitive imaging layer is in contactwith said adhesive layer.
 8. The laminate of claim 1 in which saidthermally transmissive film is a strip of flexible material supportingsaid thermosensitive imaging layer.
 9. The laminate of claim 1 in whichsaid thermally transmissive film has a first thickness measured betweensaid front and back surfaces of the thermally transmissive film and saidsubstrate has a second thickness measured between said front and backsurfaces of the substrate, and said first thickness is less than saidsecond thickness.
 10. The laminate of claim 9 in which said firstthickness is less than 10 microns.
 11. The laminate of claim 9 in whichsaid second thickness is more than said first surface by at least anorder of magnitude.
 12. The laminate of claim 9 in which said frontsurface of the substrate has an average peak-to-valley roughness that islarger than an average peak-to-valley roughness of said back surface ofthe transmissive film.
 13. The laminate of claim 12 in which saidthermosensitive imaging layer has an average thickness that is more thanthe average roughness of the back surface of the transmissive film andless than the average roughness of the front surface of the substrate.14. The laminate of claim 13 in which said thermosensitive imaging layeris applied as a coating on said transmissive film.
 15. The laminate ofclaim 14 further comprising a friction-reducing coating applied oversaid front surface of the thermally transmissive film to protect thermalprint heads from abrasion.
 16. The laminate of claim 15 in which saidfront surface of the transmissive film is receptive to inks.
 17. Thelaminate of claim 1 in which said thermally transmissive film is also anoptically transmissive film so that the images formed in thethermosensitive imaging layer are visible through said film.
 18. Thelaminate of claim 17 in which said substrate is opaque.
 19. A method ofdirect thermal printing the laminate of claim 1 including the step ofapplying concentrations of heat to said front surface of the thermallytransmissive film resulting in the formation of images within saidthermosensitive imaging layer.
 20. The method of claim 19 in which athermal print head is used to apply the concentrations of heat.
 21. Themethod of claim 20 in which the images are formed in saidthermosensitive imaging layer by a chemical interaction between a dyeprecursor and a color developer induced by the transmissions of heatthrough said thermally transmissive film.
 22. A direct thermal printablelaminate comprising: first and second substrates located adjacent toeach other and each having first and second surfaces; a thermosensitiveimaging layer applied as a coating on said second surface of the firstsubstrate; said thermosensitive imaging layer having a color developingmechanism reactive to transmissions of heat through said first substratefor forming images within said thermosensitive imaging layer; saidsecond surface of the first substrate being bonded to said first surfaceof the second substrate so that said thermosensitive imaging layer islocated between said first and second substrates; said first substratebeing of reduced thickness with respect to said second substrate fortransmitting concentrations of heat required to form images in saidthermosensitive imaging layer from a thermal print head; and at leastone of said first and second substrates being optically transmissive forviewing images formed in said thermosensitive imaging layer.
 23. Thelaminate of claim 22 in which said second surface of the first substrateand said first surface of the second substrate have respective surfaceforms and said thermosensitive imaging layer takes the form of saidsecond surface of the first substrate.
 24. The laminate of claim 22 inwhich said first surface of the second substrate has an averagepeak-to-valley roughness that is larger than an average peak-to-valleyroughness of said second surface of the first substrate.
 25. Thelaminate of claim 24 in which said thermosensitive imaging layer has anaverage thickness that is more than the average roughness of the secondsurface of the first substrate and less than the average roughness ofthe first surface of the second substrate.
 26. The laminate of claim 22in which said thickness of the first substrate is less than 10 microns.27. The laminate of claim 22 further comprising a friction reducingcoating applied to said first surface of the first substrate to protectthe thermal print head from abrasion.
 28. The laminate of claim 22further comprising an adhesive layer located between saidthermosensitive imaging layer of the first substrate and said firstsurface of the second substrate for bonding said first and secondsubstrates.
 29. The laminate of claim 28 further comprising a barrierlayer located between said thermosensitive imaging layer and saidadhesive layer for preventing migration of contaminants from saidadhesive layer to said thermosensitive imaging layer.
 30. The laminateof claim 22 in which said first substrate is and optically transmissivefilm.
 31. The laminate of claim 30 in which said second substrate isopaque.
 32. The laminate of claim 28 in which said adhesive layer is afirst adhesive layer and further comprising a second adhesive layerlocated adjacent to said second surface of the second substrate.
 33. Thelaminate of claim 32 further comprising a release layer located adjacentto said first surface of the first substrate.
 34. The laminate of claim33 in which said first and second substrates unwindable together from aroll in which said second adhesive layer is in contact with said releaselayer.
 35. A method of direct thermal printing the laminate of claim 22including the step of applying concentrations of heat to said firstsurface of the first substrate resulting in the formation of imageswithin said thermosensitive imaging layer.
 36. The method of claim 35 inwhich a thermal print head is used to apply the concentrations of heat.37. The method of claim 36 in which the images are formed in saidthermosensitive imaging layer by a chemical interaction between a dyeprecursor and a color developer induced by the transmissions of heatthrough said first substrate.
 38. A self-wound direct thermal printabletape comprising: a film having front and back surfaces; a release layeron said front surface of the film; a thermosensitive imaging layer onsaid back surface of the film; said thermosensitive imaging layer havinga color developing mechanism reactive to transmissions of heat throughsaid film for forming images within said thermosensitive imaging layer;a substrate having front and back surfaces; a first adhesive layer onsaid front surface of the substrate for bonding said substrate to saidfilm; a second adhesive layer on said back surface of the substrate forbonding said substrate to another substrate; and said film beingunwindable together with said substrate from a roll in which said secondadhesive layer is in contact with said release layer.
 39. The tape ofclaim 38 in which said film is optically transmissive so that imagesformed within said thermosensitive imaging layer are visible throughsaid film.
 40. The tape of claim 39 in which any layers located betweensaid thermosensitive imaging layer and said first adhesive layer aresuccessively bonded to said thermosensitive imaging layer.
 41. The tapeof claim 40 further comprising a barrier layer located between saidthermosensitive imaging layer and said first adhesive layer forpreventing migration of contaminants from said first adhesive layer tosaid thermosensitive imaging layer.
 42. The tape of claim 39 in whichsaid thermosensitive imaging layer is bonded to said first adhesivelayer.
 43. The tape of claim 38 in which said film is a strip offlexible material.
 44. The tape of claim 43 in which saidthermosensitive imaging layer is applied as a coating on said film. 45.A method of using the tape of claim 38 including the step of laminatingthe tape to said another substrate by positioning said second adhesivelayer in contact with said another substrate.
 46. A method of printingon the tape of claim 38 including the step of applying concentrations ofheat with a thermal print head to said first surface of the filmresulting in the formation of images within said thermosensitive imaginglayer.
 47. A direct thermal printable film for use with a substrate formaking a direct thermal printable laminate comprising: an optically andthermally transmissive film having front and back surfaces; a layer offriction-reducing material applied to said front surface of thetransmissive film; a layer of thermosensitive imaging material appliedto said back surface of the transmissive film; said front and backsurfaces having respective surface forms and said thermosensitiveimaging material taking the form of said back surface of the film; andsaid thermosensitive imaging material having a color developingmechanism reactive to transmissions of heat through said film forforming images within said thermosensitive imaging layer that arevisible through said film.
 48. The film of claim 47 in which a layer ofadhesive is applied over said layer of thermosensitive imaging materialfor attaching the film to the substrate prior to printing.
 49. The filmof claim 48 in which said layer of friction-reducing material is arelease material for also protecting said layer of adhesive prior touse.
 50. The film of claim 49 in which said film is unwindable from aroll in which said layer of adhesive is in contact with said layer ofrelease.
 51. The film of claim 48 further comprising a layer of barriermaterial between said layer of thermosensitive imaging material and saidlayer of adhesive for preventing migration of contaminants from saidlayer of adhesive to said layer of thermosensitive imaging material. 52.The film of claim 48 in which said optically and thermally transmissivefilm has a thickness no greater than 10 microns for transmitting thermalpatterns through said film.
 53. A method of making a direct thermalprintable laminate using the direct thermal printable film of claim 47including the step of laminating the back surface of the transmissivefilm containing the layer of thermosensitive imaging material to a frontsurface of a substrate that does not as readily transmit heat as thetransmissive film.
 54. The method of claim 53 including the further stepof applying a layer of adhesive between the layer of thermosensitiveimaging material and the front surface of the substrate prior to saidstep of laminating.
 55. The method of claim 54 including the furtherstep of applying a layer of barrier material over said layer ofthermosensitive imaging material prior to said step of laminating.
 56. Adirect thermal printable film comprising: a thermally transmissive filmhaving front and back surfaces; a layer of thermosensitive imagingmaterial applied to said back surface of the transmissive film; saidthermosensitive imaging material having a color developing mechanismreactive to transmissions of heat through said film for forming imageswithin said thermosensitive imaging layer; and said thermallytransmissive film having a thickness no greater than 10 microns topermit transfers of heat from a direct thermal print head through saidthermally transmissive film for forming images within saidthermosensitive imaging layer.
 57. The film of claim 56 in which saidthermally transmissive film is also optically transmissive so that theimages within said thermosensitive imaging layer are visible throughsaid film.
 58. The film of claim 56 further comprising a layer offriction-reducing material applied to said front surface of thetransmissive film.
 59. The film of claim 56 in which said front and backsurfaces have respective surface forms and said thermosensitive imagingmaterial takes the form of said back surface of the film.
 60. The filmof claim 56 in which said film is windable and unwindable from a rollfor use in a laminating machine for joining said film to anothersubstrate.
 61. A method of making a direct thermal printable laminatecomprising the steps of: feeding a film of thermally transmissivematerial having front and back surfaces through a coating machine;applying a coating of thermosensitive imaging material on the backsurface of the film so that transmissions of heat through the film formimages within the thermosensitive imaging material; feeding a substratehaving front and back surfaces through a coating machine; applying acoating of adhesive between the coating of thermosensitive imagingmaterial and the front surface of the substrate; and laminating the filmand the substrate together so that the back surface of the film isadjacent to the front surface of the substrate.
 62. The method of claim61 in which said step of applying a coating of adhesive includesapplying the coating to the front surface of the substrate prior tolaminating the film and substrate together.
 63. The method of claim 61including the further step of dividing the film into narrower stripsfollowing said step of applying the thermosensitive imaging material andbefore said step of laminating.
 64. The method of claim 63 including thefurther steps of winding the narrower strips into rolls and unwindingone of the narrower strips together with unwinding a roll of thesubstrate before said step of feeding the substrate.
 65. The method ofclaim 61 including the further step of applying a barrier coating overthe coating of thermosensitive imaging material for preventing migrationof contaminants from the coating of adhesive to the coating ofthermosensitive imaging material.
 66. The method of claim 61 includingthe further step of applying a friction-reducing coating to said frontsurface of the film to reduce abrasion with a thermal print head. 67.The method of claim 61 including the further step of applying a coatingof adhesive on the back surface of the substrate.
 68. The method ofclaim 67 including the further step of applying a coating of release onthe front surface of the film.
 69. A method of making a direct thermalprintable laminate comprising the steps of: feeding a film of thermallytransmissive material having front and back surfaces through aprocessing machine, said film having a coating of thermosensitiveimaging material on the back surface of the film; feeding a substratehaving front and back surfaces through the processing machine, saidsubstrate having a thickness greater than a thickness of said film; andlaminating the film and the substrate together so that the back surfaceof the film containing the thermosensitive imaging material is adjacentto the front surface of the substrate.
 70. The method of claim 69including the further step of applying a coating of adhesive between thethermosensitive imaging material and the front surface of the substrateprior to said step of laminating.
 71. The method of claim 69 in whichsaid film has a thickness no greater than 10 microns to supporttransmissions of heat through the film to form images within thethermosensitive imaging material.
 72. The method of claim 69 includingthe further steps of separately unwinding the film and the substratefrom separate rolls prior to said steps of feeding the film andsubstrate through the processing machine.
 73. The method of claim 72 inwhich the coating of thermosensitive imaging material is applied inadvance of said step of unwinding the film.
 74. The method of claim 69in which the substrate is a first of two substrates and including thefurther step of feeding a second substrate having front and backsurfaces through a processing machine, said second substrate also havinga thickness greater than the thickness of said film.
 75. The method ofclaim 74 in which said step of laminating includes laminating a firstlength portion of the film to the first substrate and including thefurther step of laminating a second length portion of the film to thesecond substrate so that the back surface of the film containing thethermosensitive imaging material is adjacent to the front surface of thesecond substrate.